Non-canonical Wnt signaling: What is its role in bone?

Genetic determinism of bone and mineral metabolism in meat-type chickens: A QTL mapping study

Skeletal integrity in meat-type chickens is affected by many factors including rapid growth rate, nutrition and genetics. To investigate the genetic basis of bone and mineral metabolism, a QTL detection study was conducted in an intercross between two lines of meat-type chickens divergently selected for their high (D +) or low (D -) digestive efficiency. Tibia size (length, diameter, volume) and ash content were determined at 3 weeks of age as well as phosphorus (P) retention and plasma concentration. Heritability of these traits and their genetic correlations with digestive efficiency were estimated. A QTL mapping study was performed using 3379 SNP markers. Tibia size, weight, ash content and breaking strength were highly heritable (0.42 to 0.61). Relative tibia diameter and volume as well as P retention were strongly and positively genetically correlated with digestive efficiency (0.57 to 0.80). A total of 35 QTL were identified (9 for tibia weight, 13 for tibia size, 5 for bone strength, 5 for bone mineralization, 2 for plasma P concentration and 1 for P retention). Six QTL were genome-wide significant, and 3 QTL for tibia relative volume, weight and ash weight on chromosome 6 were fixed, the positive allele coming from the D-line. For two QTL for ash content on chromosome 18 and relative tibia length on chromosome 26, the confidence intervals were small enough to identify potential candidate genes. These findings support the evidence of multiple genetic loci controlling bone and mineral metabolism. The identification of candidate genes may provide new perspectives in the understanding of bone regulation, even beyond avian species.

Targeting the Wnt signaling pathway for the development of novel therapies for osteoporosis

A number of anti-osteoporotic drugs, predominantly inhibitors of bone resorption, are currently used in the management of patients with osteoporosis to reduce the risk of fractures. While the management of the disease has improved significantly, there are still unmet needs, mainly due to a lack of agents able to replace bone that has already been lost. Human and animal genetics have identified the pivotal role of the Wnt signaling pathway in the regulation of bone formation by the osteoblasts and have made it a very attractive target for the development of novel treatments for osteoporosis. In this article, we review evidence that supports the targeting of components of the Wnt signaling pathway for the design of bone-forming treatments for osteoporosis.